New York City -- The National Retail Federation said Thursday that it expects retail sales growth of 4% this year, the biggest increase since 2006.

However, the group warned that shoppers are likely to remain cautious as they cope with slow job growth and rising prices.

The NRF said it expects retail sales to reach $2.47 trillion in 2011, up from $2.37 trillion in 2010, excluding automobiles, fuel and restaurants.

That increase would be higher than the past decade's average annual growth rate of 3.1% and 2010's increase of 3.7%. Retail sales rose 4.7% in 2006, which is still under the 5% rate that indicates a robust economy.

"Consumers will continue to be thoughtful about what they're spending, but they're certainly feeling better," said Jack Kleinhenz, NRF's chief economist.

NRF's forecast is not adjusted for inflation, and the figures include online sales from physical stores but not from such companies as Amazon.com that operate only on the web.